The rectangular collimator is a dental device that has been used in conjunction with external positioning devices intended to give proper geometric alignment between the X-ray generator, the patient's teeth and the X-ray film or digital radiographic sensor. The purpose of the rectangular collimator is to restrict the size of the X-ray beam to approximately the size of the imaging field of the film or sensor. This protects the patient against unnecessary radiation exposure and improves image quality by reducing side scatter.
Such devices also improve image quality by reducing X-ray side scatter from anatomic structures outside the imaging field of view but within the uncollimated X-ray beam.
The main deficiency in the current design of all rectangular collimating devices is the user's inability to adjust the size of the rectangular opening to match that of the actual X-ray film or digital sensor size to minimize the non-imaging patient X-ray exposure.
There are three common sizes of intra oral x-ray film or digital sensors commonly used in dentistry: Size 0, size 1, and size 2. The existing rectangular collimators are usually slightly larger than the size 2 X-ray film or digital sensor.
A rectangular collimating device with the adjustability for the three different size imaging fields would further reduce the patient's X-radiation exposure by matching the rectangular opening of the collimator to the specific film or sensor size used.